1. Field of the Art
Generally, embodiments of the present invention relate to methods and devices for implanting live cells within a body and providing nutrients to the live cells. The nutrients can be transported from an environment external to the body or from within the body.
2. Description of the Related Art
Diabetes is a group of widespread diseases in which there are high blood sugar levels over a prolonged period. If left untreated, diabetes can cause many complications. Acute complications can include diabetic ketoacidosis, nonketotic hyperosmolar coma, or death. Serious long-term complications include heart disease, stroke, chronic kidney failure, foot ulcers, and damage to the eyes. Diabetes is due to either cells in the pancreas not producing insulin (type-I diabetes) or not responding properly with the insulin production and release (type-II diabetes).
Pancreatic islets or islets of Langerhans, referred to herein as islets, are clusters of cells, containing mostly beta cells that secrete insulin. In people suffering from type-I diabetes, the islets are destroyed. One of medical solutions is to implant islets. In islet transplantation, cells are isolated from a donor pancreas and transplanted into type I diabetic patients. Once implanted, the transplanted islets begin to make and release insulin, thereby helping patients potentially avoiding the need of daily insulin injections.
Islet transplantation into the liver of diabetic patients has been studied for decades as a long-term treatment of type-I diabetes by normalizing blood sugar levels and preventing life-threatening hypoglycemic episodes. However, this “intrahepatic” islet transplantation results in chronic decline of islet function due to inflammation, immune response, and toxic environment to islets.
Attempts have been made to transplant islets into sites outside the liver. For example, the subcutaneous site (e.g., under the skin) is promising as it provides a large area and easy access for transplantation. However, low oxygen supply to implanted islets within the subcutaneous microenvironment is detrimental to islet survival. Specifically, the survival of islets depends on sufficient supply of oxygen to the islets at the site of implantation. Inadequate flow of oxygen, and/or of other nutrients, leads to the death of the islets, thereby negating any benefits of the implantation.
For a period of time after a subcutaneous implantation, a risk for ischemia exists. Ischemia is caused by inadequate blood flow due to the lack of adequate vascular structure in the subcutaneous implantation site. Oxygen supply to the implanted islets is not proper until sufficient vascular growth is achieved around the islets. Accordingly, for the islets to survive during the period of time between implantation and vascular growth, oxygen should be adequately supplied from other sources. No solutions exist currently for the adequate oxygen supply in islet transplantation outside of the liver.
Therefore, current treatments of diabetes based on islet implantation have a number of distinct disadvantages that need to be overcome.